Posttraumatic stress disorder (PTSD) is a highly prevalent and pernicious disorder, with a frequently chronic course. There are far-reaching and devastating interpersonal relationship problems associated with chronic PTSD than can maintain or aggravate its course. These problems can also interfere with successful treatment delivery, and may be addressed to improve treatment compliance, efficacy of treatment, and maintenance of gains. A number of clinicians and researchers have called for the inclusion of significant others in PTSD treatment because of these reasons. In an effort to improve upon the treatment of chronic PTSD and its broader functional impairments, the overall goal of this R34 Exploratory Research Grant is to refine and adapt a manualized Cognitive-Behavioral Couples Therapy (CBCT) for PTSD, and to test it against a delayed treatment condition. Phase 1 of the project aims to (1) refine the existing CBCT for PTSD manual;(2) develop a treatment fidelity measure;and (3) finalize the assessment protocol by treating a series of 10 couples in which one member of the couple is diagnosed with chronic PTSD. This phase would ensure that the treatment is sufficiently flexible to address a range of traumatized individuals and couples, and that it has the necessary elements for conducting a controlled trial. Phase 2 of the project consists of a randomized controlled trial of the refined therapy to determine its efficacy and estimate other intervention parameters. The sample will consist of 40 community couples including one person diagnosed with chronic PTSD. The couples will be randomized to receive the therapy immediately or be placed on a waiting list to receive the treatment. The primary hypothesis is that CBCT for PTSD will be more efficacious than the delayed treatment control in reducing overall PTSD symptoms, as measured by clinician interview, across treatment. Secondary and exploratory hypotheses relate to improved self-reported PTSD symptoms, co-morbid conditions, partner outcomes, and relationship functioning in the CBCT for PTSD immediately versus delayed treatment condition. An uncontrolled follow-up assessment of the immediate CBCT for PTSD condition at three months, and a replication of the primary results in the delayed treatment group are planned. The longer-term goal of this line of research is to conduct a Stage III trial of CBCT for PTSD compared to state-of-the-art individual PTSD treatment through an R01 grant-funded study. Posttraumatic Stress Disorder (PTSD) is highly prevalent, and comes at great cost to individuals, their loved ones, and society. The current project aims to develop a couples treatment for PTSD that would decrease individual PTSD symptoms, as well as improve the survivor's intimate relationship functioning and the well- being of their intimate partner. It is hoped that this treatment will ultimately decrease the prevalence and burden of this significant and growing public health problem.